/Engine/Source/Runtime/InteractiveToolsFramework/Public/BaseGizmos/GizmoMath.h
Find the nearest point to QueryPoint on the line defined by LineOrigin and LineDirection. Returns this point and the associated line-equation parameter
namespace GizmoMath { void GizmoMath::NearestPointOnLine ( const FVector & LineOrigin, const FVector & LineDirection, const FVector & QueryPoint, FVector & NearestPointOut, float & LineParameterOut ) }